Hybrid vehicles combine various types of drive, for example internal combustion engines and electric motors. In this context, the types of drive complement one another and compensate one anothers' drawbacks. One drawback of internal combustion engines are their exhaust gases. These are legally limited and have to be monitored during the driving mode. This monitoring is usually carried out, for example, by onboard diagnostics (OBD).
Exhaust gases of internal combustion engines are bad, in particular, in the case of dynamic operation, that is to say in the case of rapid load changes or strong acceleration, that is to say a high load. This is attenuated by the use of an electric motor. The electric motor and the associated battery therefore have a direct influence on the exhaust gas emissions of the vehicle and therefore also have to be monitored. The monitoring limit is defined here in such a way that it is signalled when the exhaust gases have worsened by a predefined factor with respect to a defined test cycle. With respect to the battery or the battery system, such states cannot be determined and there are no known conventional solutions known which monitor the state of the battery in conjunction with the exhaust gas emissions.
Laid-open patent application DE 10 2005 040 783 A1 discloses a method for controlling a vehicle drive unit, wherein the drive unit comprises at least two individual motors. According to the solution described in DE 10 2005 040 783 A1, a total actual torque is calculated from the individual actual torques of the at least two individual motors and compared with a permissible total torque.